Easter eggs and nods to previous seasons can be found throughout the show going as far back as season one.

In the season five premiere, Meredith dreamt of Derek being killed in a car accident. Six seasons later, that's exactly how he died.

After 14 seasons and 312 episodes, it's safe to say that "Grey's Anatomy" is a powerhouse of a show with a huge following. Fans are always looking for clues that Shonda Rhimes may have left, letting us know what could be to come in the next episodes.

Fans of "Grey's Anatomy" have learned to pay close attention to every single detail in the show, because sometimes even the littlest things can predict huge events later on. The special 300th episode was full of Easter eggs and nods back to previous seasons, but similar moments are sprinkled all throughout the show — even going back as far as season 1.

Was Derek's passing planned from the start? Will Christina Yang ever come back? Did you know that one episode of "Grey's Anatomy" was actually a social experiment on the audience? Shonda Rhimes and "Grey's Anatomy" just keeps us guessing and surprises the fans with new information at every turn.

Alex Karev's CGI appearance

Believe it or not, "Grey's Anatomy" almost didn't include fan favorite Alex Karev. He's one of only four characters who has made it through all 14 seasons — along with Meredith Grey, Miranda Bailey, and Richard Weber — but Karev almost wasn't a character on the show at all.

When the pilot episode was shot, Karev wasn't even present. He had to be digitally added into the episode later, a detail hard to ignore after seeing it. Apparently, the writers realized they wanted a male who could play the opposite of George O'Malley.

Karev's "rough around the edges" character was the perfect opposite to the nervous, shy O'Malley. It's a good thing the writers decided to add him because at this point it's hard to picture what "Grey's Anatomy" would be without Karev.

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"Dream a Little Dream of Me"

Derek died the exact way that Meredith dreamed about — six seasons ahead of time.
ABC

The episode titled "Dream a Little Dream of Me" is the first episode of the fifth season of "Grey's Anatomy." There are many things about this episode, including the title name, that may have foreshadowed Derek Shepherd's eventual passing later in the series.

In this episode, Meredith is having vivid dreams of Derek losing his life in an accident. As most fans know, Derek does eventually pass from complications related to a car accident in season 11. Not only did Meredith's dreams predict how Derek would leave, six seasons ahead of time, she even says at one point in the episode, "It's the nightmares that always seem to become reality. The person that invented the phrase 'Happily ever after' should have his a- kicked, so hard!"

Did the writers really know this early how Derek's life would end, and that they wouldn't get their "happily ever after," or was it all one big coincidence?

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Cristina Yang's article

It's easy to miss.
ABC

Ever since fan favorite Cristina Yang left the show on the season 10 finale, everyone has been wondering if she'll make a return. Without her "person," Meredith just hasn't been the same, and people have been speculating for a while now that Yang will make a comeback.

We may have gotten a hint of her return in a recent episode where Meredith asks Teddy if she's read Cristina's latest article.

The camera then briefly cuts to a shot of the article along with Cristina's picture, which was definitely quick and easy to miss if you looked away even for a second. It could just be a way of keeping Cristina relevant in Meredith's life — we like to think they stay in contact way more than the show lets on — or it could be an actual hint that we may be seeing more of Cristina again soon.

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The original five

They each had surgical complications of their own.
ABC

For a group of best friends who are interning at the same hospital, these five sure have been through their share of tragedies. It's understandable that as surgical interns you deal with other people's tragedies every day, but have you ever noticed that all of the original five had surgical complications of their own?

In season one, Christina had her ectopic pregnancy, and George was dragged under a bus trying to save someone and passed after several surgeries. Izzy is the easiest to remember, also going through several surgeries for her cancer. Then we have Karev, who survived a gunshot wound to the chest, and Meredith, who needed an emergency c-section as well as surgery after the fact on her spleen.

In reality, five interns at the same hospital all getting surgery within a couple years of each other would be pretty rare, but maybe the show just doesn't want us to be happy.

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The gang's doppelgangers

They even dressed similarly to the original characters.
ABC/Mitch Haaseth

There were plenty of Easter eggs in the 300th episode of "Grey's Anatomy" that fans caught on to. The main callback of the episode to previous seasons was the doppelgangers of George, Cristina, and Izzy all come into the hospital that day for treatment.

Though it was clear that they looked like Meredith's old friends, the details go even further.

Most fans may not have noticed that the doppelgangers not only looked like George, Cristina, and Izzy, but they were wearing similar clothes to what the originals wore in the pilot episode. George had on a brown coat, Cristina had on a leather jacket, and Izzy wore a pink/purple sweater. This small detail just added more to the nostalgia, making us miss our favorite interns even more.

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April was actually pregnant

Talk about perfect timing.
ABC

Most times when actors get pregnant, it doesn't coincide with the characters they play on TV. This often leads to awkward pregnancy cover-ups, and sometimes even absences from the show for a time.

In Sarah Drew's case, her character April Kepner had a pregnancy story arc while she was carrying a baby in real life.

In fact, only 10 hours after she fake delivered her baby on the show, Drew actually went into labor and delivered her own baby girl. Talk about perfect timing!

Drew talked to "The Hollywood Reporter" about how strange and special her pregnancy journey was. She said, "I was watching the episode last week and got super emotional just looking at my belly because I didn't know my daughter's name yet, I didn't know she was girl yet and there I am looking at my belly with her inside of me and there was something so crazy weird about seeing that. It was emotionally intense [shooting that] for sure."

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Amelia's sly diss

She took a dig at President Trump.
ABC

In another one of those "blink and you might miss it" moments, the writers threw in a little political joke into an otherwise serious situation. As most fans know, Amelia Shepherd, Derek's sister, and skilled brain surgeon, at one point had a brain tumor of her own.

The tumor almost completely destroys her relationships and her life, until finally it is removed by her friend and old colleague Tom Koracick. Amelia's recovery is slow and concerning at first, but thankfully she eventually gets better.

When Tom is clearing Amelia for release, he asks her a few general questions including, "where are you" and "what year is it" to test her thinking abilities. When he asks her if she knows who the current president is, Amelia says "I wish I didn't."

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Derek's final wish

Why was no one else there?
ABC

There are so many references to Derek's passing early on in the series that come true, it's easy to wonder if the writers knew all along what would happen to him. Back in season one, Derek tells Meredith that if he is ever in a coma or on his last legs that he wants nothing more than for his sisters to be by his side for his final moments.

Fast forward to season 11, where this is exactly the case, and Meredith doesn't honor his wishes. Did she not remember, or just not care? Either way, it's hard to see Derek go without the family by his side that he wanted.

In the most recent season, Derek's sister Amelia actually brings up to Meredith that she regrets and is even angry about not being there for Derek's last moments. It's as if she knew he would have wanted her there — which he did.

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M.A.G.I.C.

She may have been referring to the original five interns.
ABC

If Meredith Grey is known for one thing on "Grey's Anatomy," it's her beginning and end of the show voiceovers. Her reflective monologues always make us think about what we just saw, or what's to come, but in the 300th episode final voiceover, something even more special was thrown in.

While Meredith is looking up at the observation room and seeing her late mother Ellis Grey clapping and finally being proud of her, Meredith mentions "magic," which could easily be interpreted as talking about her surgical success or seeing her mother. This may be true, but we also have to take into consideration the doppelgangers of her friends who appear in this episode.

When Meredith says, "we are forced to acknowledge that certain kinds of magic exist," it turns out she may have been referring to the original five. MAGIC is an acronym for their names: Meredith, Alex, George, Izzy, and Christina.

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The deadly MRI

Any trained surgeon would know that she could not get an MRI.
ABC

Even fans who know every plot detail may have missed this small mistake, but anyone who knows how an MRI machine works were probably confused to see a woman with a fork in her neck ordered to get an MRI.

It's a funny story of how Sylvia ends up with a fork in her neck. While she and her husband were on vacation, Sylvia decided to give him some "special attention" under a dinner table. Because of a brain aneurysm that she wasn't aware of, Sylvia uncontrollably bit down on her husband, who reacted by stabbing her in the neck with a fork.

But that's not the worst part! The worst part is that trained surgeons who should know that an MRI machine is basically a big magnet, ordered a woman with metal in her neck to go into the machine. In reality, the fork would have been pulled out of her neck and endangered her life.

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Non-existent nurses

Credit should be given where it's due.
ABC

If you've ever watched "Grey's Anatomy" and wondered, "where are all the nurses?" You're not alone.

While the show does a decent job of keeping them in the background, the nurses of Grey-Sloan hospital rarely do their nursing duties, and we often find ourselves watching surgeons perform tasks that usually wouldn't be a part of their jobs.

It's understandable that to keep the main characters relevant they need to check on patients and be an active part of each surgery, but in the real world, nurses do far more than they're given credit for on the show.

Nurses are an incredibly important part of how a hospital is run, and they are often the most hands-on when it comes to patients. "Grey's Anatomy" doesn't completely ignore its nurses, but we wish they would give a little more credit where credit is due.

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The secret experiment

The episode was meant to change negative misconceptions about pregnancies in HIV positive mothers.
ABC

Unbeknownst to almost everyone, "Grey's Anatomy" was at one time a part of a secret social experiment. The episode "Piece of My Heart" was influenced by an organization called The Kaiser Foundation. The foundation wanted to see if they could change people's common negative misconceptions about HIV positive pregnancies.

A woman named Sarah and her husband came to Grey-Sloan to have Sarah's pregnancy terminated. Their reason was that Sarah was HIV positive, and she didn't want to bring an infected baby into the world. Izzy ends up convincing them that they do not need to end the pregnancy because there is a 98% chance that the baby will be completely healthy. The couple eventually decides to have the baby.

The Kaiser Foundation's hopes were that a character like Sarah, who was misinformed about HIV positive pregnancies, would help others realize the truth and become more educated on the disease themselves.

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Grey's/Station 19 crossover parallel

This was a callback to Meredith's incident as an intern.
ABC

When "Grey's Anatomy" did a cross-over episode with its spin-off show "Station 19," there were some parallels that only true "Grey's Anatomy" fans would recognize.

In this crossover episode, we get introduced to our new Shondaland heroine and firefighter Andy. She shows up at Grey-Sloan inside of an ambulance, and in a quick decision, shoves her hand into the patient's chest to stop bleeding. The only problem is, if she moves her hand again, the patient will pass away.

This was a callback to when Meredith was an intern and had a similar incident, where she took over the place of another intern keeping her hand on a bomb inside a patient. Just like Andy, Meredith couldn't move, or the patient would pass — as would she and others around her!

It's a perfect bonding moment for the two leading ladies, and Meredith refuses to leave Andy's side and walks her through the entire process, encouraging her all the way.

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Hidden pregnancies

Capshaw wore a lot of black.
ABC

Unfortunately, not everyone's pregnancies can coincide with their characters like April Kepner. More times than not, some measures have to be taken to hide an actor's pregnancy, and it's definitely not an easy task.

Both Ellen Pompeo and Jessica Capshaw — who play Meredith and Arizona — were pregnant at times during the show when their characters were not.

In order to hide Pompeo's stomach, the writers gave Meredith an easy out. She ends up donating liver to her father, which puts her on bed rest for quite a while. The big pillows and fluffy blankets were the perfect way to hide her belly.

Capshaw, on the other hand, didn't have it so easy. Instead of getting to hide behind blankets, they just dressed her in a lot of black outfits with jackets that helped hide her bump. Never underestimate the power of camera angles!

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